Endometriosis is a disease wherein endometrium or endometrium-like tissue ectopically proliferates at a site other than the inner surface of the cavity of uterus which is the natural site thereof. The cause of endometriosis is unknown, and therapies such as separation of the adhered tissues by surgery, administration of hormones and administration of analgesics are performed. However, these therapies are symptomatic treatments, and no complete therapy exists.